By Mark D. Zimmerman
MELVILLE, New York — More than ten years ago, scientists began to develop lab-grown meat derived from animal cells, leading to questions of kashrut among Jewish authorities. Most agree that the product can be kosher if the animal from which the cells are taken is a kosher animal, and the production process is monitored and certified by a kosher certification agency. Recently, scientists have had success creating lab-grown milk by inserting certain genes into a yeast or fungus. What is the current thinking about the kosher status of that product?
A. Lab-grown milk is considered to be milchig (dairy) because it is produced from cow’s milk cells.
B. Lab-grown milk is considered to be fleishig (meat) because it is produced from cow cells.
C. Lab-grown milk is considered to be pareve (neither meat nor dairy) because it is made from a synthetic gene and not from a real cow cell.
D. Because the rabbis simply can’t agree on whether lab-grown milk is milchig, fleishig, or pareve, the bet din (religious court) has decided to call it milchig on Sunday and Wednesday, fleishig on Monday and Thursday, and pareve on Tuesday and Friday. On Shabbat the rabbis have ruled that only schnapps can be drunk.
E. In Judaism there is a concept of mar’it ayin, where appearance matters. Even if something is certified kosher, if it would look otherwise to observers, it would therefore be considered unacceptable unless the user made the distinction clear. For example, it is recommended that when drinking almond milk with meat that the label of the almond milk be visible to others. Similarly, because of the concept of mar’it ayin, it is recommended that when drinking lab-grown milk with a meat meal in public, the scientists who created the product should be sitting next to you in their lab coats.
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Link to answer: https://rrrjewishtrivia.com/lab-grown-milk-answer.html